Field
The disclosed embodiments relate to batteries for portable electronic devices. More specifically, the disclosed embodiments relate to the coupling of multiple conductive tabs to each electrode of a battery cell to facilitate current flow in the battery cell.
Related Art
Rechargeable batteries are presently used to provide power to a wide variety of portable electronic devices, including laptop computers, tablet computers, mobile phones, personal digital assistants (PDAs), digital music players and cordless power tools. The most commonly used type of rechargeable battery is a lithium battery, which can include a lithium-ion or a lithium-polymer battery.
Lithium-polymer batteries often include cells that are packaged in flexible pouches. Such pouches are typically lightweight and inexpensive to manufacture. Moreover, these pouches may be tailored to various cell dimensions, allowing lithium-polymer batteries to be used in space-constrained portable electronic devices such as mobile phones, laptop computers, and/or digital cameras. For example, a lithium-polymer battery cell may achieve a packaging efficiency of 90-95% by enclosing jelly rolls of wound electrodes and electrolyte in an aluminized laminated pouch. Multiple pouches may then be placed side-by-side within a portable electronic device and electrically coupled in series and/or in parallel to form a battery for the portable electronic device.
However, wound battery cell structures such as jelly rolls may have high internal resistances that preclude efficient current distribution and/or flow during high transient discharge currents. For example, a pulse discharge of a lithium-polymer battery cell containing a jelly roll may cause a significant voltage drop in the battery cell and/or an imbalance in the internal current distribution of the battery cell. In turn, the full discharge capacity of the battery cell may not be utilized. For example, a −4 C pulse discharge of a lithium-polymer battery cell may cause the voltage of the battery cell to drop below a 2.8V discharge-termination voltage for the battery after only 67% of the battery cell's capacity is used.
Consequently, use of wound battery cell structures may be facilitated by mechanisms for improving the transient voltage responses of the battery cell structures to high transient discharge currents.